Question1) Why do we need to separate different components of a mixture? Give two examples.
solution1: there are many harmful and unwanted substances among the different components of the mixture. so for the removal of these harmful and unwanted substances, we need to separate them. For example:
(a) Tea leaves are separated from the liquid with a strainer while preparing tea.
(b) Stone pieces from wheat, rice or pulses are picked out by hand.
Question 2) What is winnowing? Where is it used?
solution2: separating heavier and lighter components of a mixture by wind or by blowing air is called winnowing. Farmers used this process which is known as winnowing to separate lighter husk particles from heavier seeds of grain.
Question3) How will you separate husk or dirt particles from a given sample of pulses before cooking?
solution 3: Husk or dirt particles are very light particles that fly away by the process of winnowing. so husk can be separated by winnowing.
Question4) What is Sieving? Where can it be used?
solution4: to separate fine particles from bigger particles a sieve is used and this process is known as sieving. It is used in flour mills or at construction sites. In the flour mill, husks and stones are removed from wheat, and Pebbles and stones are removed from sand by sieving.
Question5) How will you separate sand and water from their mixture?
solution5: sedimentation and decantation are the methods used to separate sand and water from their mixture. After leaving this mixture for some time, sand particles being heavier than water settle down in the container after that water is transferred to another container and this is how sand and water separate.
Question 6) Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
solution6: yes, it is possible to separate sugar from wheat by sieving. Due to the difference in the size of particles, sugar will stay on the sieve and wheat flour will pass through it.
Question 7) How would you obtain clear water from a sample of muddy water?
solution7: through filtration, we will obtain clear water from a sample of muddy water. For filtration, we use filter paper which is a paper that has very fine pores in it. The mixture of muddy water is poured on the filter paper and solid particles remain on the filter and clear water is obtained.
Question 8) Fill in the blanks:
(a) The method of separating the seeds of paddy from its stalks is called __________.
(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of ______.
(a) Salt is obtained from sea water by the process of ____________.
(b) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called ____________.
Solution8)
(a) The method of separating the seeds of paddy from its stalks is called threshing.
(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of filtration.
(a) Salt is obtained from seawater by the process of evaporation.
(b) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called sedimentation and decantation.
Question 9) True or false?
(a) A mixture of milk and water can be separated by filtration.
(b) A mixture of powdered salt and sugar can be separated by the process of winnowing.
(c) Separation of sugar from tea can be done with filtration.
(d) Grain and husk can be separated with the process of decantation.
Solution 9)
(a) A mixture of milk and water can be separated by filtration. False
(b) A mixture of powdered salt and sugar can be separated by the process of winnowing. False
(c) Separation of sugar from tea can be done with filtration. False
(d) Grain and husk can be separated with the process of decantation. False
Question 10) Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving sugar ? In which case would it be possible to dissolve more sugar?
solution10) more the temperature more the sugar will dissolve so we should add ice after the sugar is dissolved because after adding sugar the temperature cools down and sugar will not dissolve properly.